Two commercial coffee decaffeination methods currently dominate the coffee industry. One of the more widely used methods is disclosed in U.S. Pat. No. 2,309,092 to Berry et al. wherein green coffee beans are extracted with a caffeine-deficient aqueous extract of green coffee solubles. After extraction, the caffeine-laden extract is stripped of caffeine by contact with a halogenated organic solvent, such as methylene chloride. The second widely used decaffeination method involves extracting the green coffee beans directly with an organic solvent as disclosed in U.S. Pat. No. 3,771,263 to Patel et al.
Early attempts at decaffeinating with an adsorbent are disclosed in U.S. Pat. Nos. 1,930,257 to Stelkens and 2,198,859 to Burgin wherein activated carbon is used to adsorb caffeine from an extract. The disclosed inventions are commercially impractical though, because substantial amounts of non-caffeine solids, particularly chlorogenic acid, are adsorbed from the extract along with the adsorption of caffeine.
Recent disclosures are directed to making decaffeination with adsorbents more feasible. One process wherein the carbon is treated with a solution of carbohydrates prior to decaffeination is described in Canadian Pat. No. 1,123,656. While the method limits the net loss of non-caffeine solids from the coffee extract, the extract does lose chlorogenic acid in what is believed to be an essentially even exchange of chlorogenic acid for carbohydrates adsorbed on the activated carbon. The loss of the chlorogenic acid from the coffee extract may have negative flavor implications.
It is an object of the present invention to provide a method of decaffeinating an aqueous coffee extract using a treated activated carbon, which method limits the net loss of non-caffeine solids from said extract.
A further object of the invention is to provide a decaffeination method using a treated activated carbon, which method substantially reduces the loss of chlorogenic acid from an extract.